Chapter 5 Energy In Action, Work, Power And Energy MCQs
Question 1. The rate of doing work is called
(1) Velocity
(2) Energy
(3) Power
(4) Force
Answer: (3) Power
Question 2. The unit of energy in SI system is
(1) Erg
(2) Watt
(3) Horse power
(4) Joule
Answer: (4) Joule
Question 3. One watt is equal to
(1) 1 erg/s
(2) 1 g.cm/s
(3) 1 kg.m/s
(4) 1 joule/s
Answer: (4) 1 joule/s
Question 4. One horsepower is equal to
(1) 500 W
(2) 1000 W
(3) 746 W
(4) 764 W
Answer: (3) 746 W
Question 5. Kilowatt is the unit of
(1) Energy
(2) Work done
(3) Power
(4) Force
Answer: (3) Power
Question 6. ln case of negative work, the angle between force and displacement is
(1) 0°
(2) 45°
(3) 90°
(4) 180°
Answer: (4) 180°
Question 7. In a tug-of-war, work done by the losing team is
(1) Positive
(2) Negative
(3) Zero
(4) None of these
Answer: (2) Negative
Question 8. The work done on an object does not depend upon the
(1) Displacement
(2) Initial velocity of the object
(3) Force applied
(4) Angle between force and displacement
Answer: (2) Initial velocity of the object
Question 9. Which one of the following is not a unit of energy?
(1) Kilowatt
(2) Joule
(3) Newton-metre
(4) Kilowatt-hour
Answer: (4) Kilowatt
Question 10. When an object falls freely under gravity, then its total energy
(1) Increases
(2) Decreases
(3) Remains constant
(4) First increases and then decreases
Answer: (3) Remains constant
Question 11. When a body moves in a circular path, everything remains unchanged except
(1) Acceleration
(2) Kinetic energy
(3) Speed
(4) Retardation
Answer: (2) Kinetic energy
Question 12. A body when raised from the floor to the top of a table, the work done depends on
(1) Weight of the body
(2) Time needed to raise it
(3) Velocity of the body
(4) Acceleration of the body
Answer: (1) Weight of the body
Question 13. A person while walking along a-road carrying a bag in hand, he does
(1) Not do work on the bag
(2) Work on the bag
(3) Work on the bag if the bag be light
(4) Work on the bag if the bag be heavy
Answer: (1) Not do work on the bag
Question 14. A mechanical system tends to attain the position of
(1) Maximum kinetic energy
(2) Minimum kinetic energy
(3) Minimum potential energy
(4) Maximum potential energy
Answer: (3) Minimum potential energy
Question 15. A body of mass m when raised from.a depth h below the earth’s surface to a position h distance above the earth, the change of potential energy will be
(1) 2 mgh
(2) Zero
(3) mgh
(4) 3 mgh
Answer: (3) mgh
Question 16. Newton meter is the unit of
(1) Work in-SI
(2) Power in SI
(3) Power in SI
(4) Work in CGS
Answer: (1) Work in SI
Question 17. Two bodies of masses 1 g and 4 g move with equal kinetic energy. Ratio of the magnitude of their momenta is
(1) 4:1
(2)\(\sqrt{2}\):1
(3) 1:2
(4) 1:16
Answer: (3) 1:2
Question 18. On application of an external force on a moving body, a body is retarded. Work done by the body is
(1) Negative
(2) Positive
(3) Zero
(4) Half
Answer: (1) Negative
Question 19. Due to winding of spring, a clock acquires
(1) Kinetic energy
(2) No energy
(3) Elastic potential energy
(4) Gravitational potential energy
Answer: (3) Elastic potential energy
Question 20. To obey the law of conservation of linear momentum during collision a condition is
(1) External force is 0
(2) Time of collision is negligible
(3) No internal force
(4) External force is maximum
Answer: (1) External force is 0
Question 21. A raindrop of radius R fell on ground from a height h. Work done by the gravitational force is proportional to
(1) \({R}^{}\)
(2) \(\sqrt{R}\)
(3) \({R}^{3}\)
(4) \({R}^{2}\)
Answer: (3) \({R}^{3}\)
Question 22. A body is moved from a point A to point B over a rough surface that possesses friction due to which x work is done. The pedy moves back from B to A on the same surface. Total work done will be
(1) Zero
(2) x
(3) 2x
(4) 3x
Answer: (3) 2x
Question 23. Which pair of physical quantities have same unit?
(1) Force and work
(2) Work and energy
(3) Power and force
(4) Work and power
Answer: (2) Work and energy
Question 24. Increase of kinetic energy equals
(1) Increase of mass
(2) Work done
(3) Increase of power
(4) Increase of velocity
Answer: (2) Work done
Question 25. Two bodies of different masses have equal kinetic energy. Momentum possessed by
(1) The body of less mass is larger
(2) The body of larger mass is larger
(3) Both the bodies are equal
(4) The body of larger velocity is larger
Answer: (2) The body of larger mass is larger
Question 26. Work is done when the point of application of force moves
(1) Perpendicular to the force
(2) In the direction of force
(3) In any direction
(4) In the direction perpendicular to force
Answer: (2) In the direction of force
Question 27. Water reserved in a dam possesses
(1) Kinetic energy
(2) Potential energy
(3) Both potential and kinetic energies
(4) No energy
Answer: (2) Potential energy
Question 28. A person performs 300 J work in 1.5 hr. Another person does 1500 J in 100 hr. The power of
(1) 1st person is greater
(2) 2nd person is greater
(3) Both the person are equal
(4) Both are zero
Answer: (1) 1st person is greater
Question 29. SI unit of energy is
(1) Joule
(2) Erg
(3) Dyne
(4) Newton
Answer: (1) Joule
Question 30. The potential energy of a boy is maximum when he is
(1) Sitting on the floor
(2) Standing on the floor
(3) Sleeping on the floor
(4) Sitting on a chair
Answer: (2) Standing on the floor
Question 31. Water stored in a dam possesses
(1) KE
(2) PE
(3) Electric energy
(4) No energy
Answer: (2) PE
Question 32. The kinetic energy of an object is K. If its mass is reduced to half, then its kinetic energy will be
(1) K
(2) 2K
(3) K/2
(4) K/4
Answer: (3) K/2
Question 33. The work done on an object does not depend upon the
(1) Force applied
(2) Initial velocity
(3) Displacement
(4) Angle between force and displacement
Answer: (2) Initial velocity
Question 34. In case of negative work, the angle between force and displacement is
(1) 0°
(2) 45°
(3) 90°
(4) 180°
Answer: (4) 180°
Question 35. In a tug-of-war, work done by the losing team is
(1) Zero
(2) Positive
(3) Negative
(4) None of these
Answer: (3) Negative
Question 36. A stone is thrown vertically upwards. It comes to rest momentarily at the highest point. What happens to its kinetic energy?
(1) It is converted into elastic potential energy
(2) It is converted into gravitational potential energy
(3) It is converted into chemical energy
(4) It is completely destroyed
Answer: (2) It is converted into gravitational potential energy
Question 37. A force of 100 N acting on a body 1000 J work. The distance through which the body is displaced is
(1) 5m
(2) 10 cm
(3) 10m
(4) 55cm
Answer: (2) 10 m
Question 38. When electric current passes through an electric bulb, electric energy is converted into
(1) Heat energy only
(2) Light energy only
(3) Both heat and light energy
(4) Both light and chemical energy
Answer: (3) Both heat and light energy
Question 39. What type of energy a raised hammer possesses?
(1) Kinetic energy
(2) Potential energy
(3) Gravitational energy
(4) No energy
Answer: (2) Potential energy
Question 40. What is the absolute unit of work in SI system?
(1) 1 kg-m
(2) 1 joule
(3) 1 erg
(4) 1 dyne
Answer: (2) 1 joule
Question 41. What is the relation between power and force?
(1) Power = force x velocity
(2) Velocity = force x power
(3) Force = power x velocity
(4) Power = force/2
Answer: (1) Power = force x velocity
Question 42. What is the amount of work performed by a person on the weight w that he carries and moves horizontally through a distance d?
(1) No work is done
(2) Work done = w xd
(3) Work done = w ÷ d
(4) Work done \(=\frac{d}{w}\)
Answer: (1) No work is done
Question 43. The dimension of energy is
(1) \(\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right]\)
(2) \(\left[\mathrm{M}^2{L}^2 \mathrm{~T}^{3}\right]\)
(3) \(\left[\mathrm{ML}^2 \mathrm{~T}^{3}\right]\)
(4) \(\left[\mathrm{ML}^3 \mathrm{~T}^{2}\right]\)
Answer: (1) \(\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right]\)
Question 44. All energies are transformed ultimately into
(1) Heat energy
(2) Kinetic energy
(3) Sound energy
(4) Electric energy
Answer: (1) Heat energy
Question 45. Which one is a scalar quantity?
(1) Force
(2) Displacement
(3) Work
(4) Velocity
Answer: (3) Work
Question 46. If the velocity of a body is doubled then kinetic energy will be
(1) Same
(2) Doubled
(3) Four times
(4) Halved
Answer: (3) Four times
Question 47. Work done in unit time is known as
(1) Power
(2) Energy
(3) Force
(4) Velocity
Answer: (1) Power
Question 48. 1 kilowatt =
(1) \(\frac{2}{3}\) HP
(2) \(\frac{4}{3}\) HP
(3) \(\frac{7}{3}\) HP
(4) \(\frac{1}{3}\) HP
Answer: (2) \(\frac{4}{3}\) HP
Question 49. What is the unit of kinetic energy is SI system?
(1) Erg
(2) HP
(3) Joule
(4) Dyne
Answer: (3) Joule
Question 50. 1 mega-watt =
(1) \({10}^3\) watt
(2) \({10}^4\)watt
(3) \({10}^6\)watt
(4) \({10}^2\) watt
Answer: (3) \({10}^6\)watt
Question 51. Kilogram-metre is the unit of
(1) Energy
(2) Power
(3) Work
(4) Velocity
Answer: (3) Work
Question 52. The dimension of power is
(1) \(\left[\mathrm{ML}^2 \mathrm{~T}^{-3}\right]\)
(2) \(\left[\mathrm{M}^2{L}^2 \mathrm{~T}^{-2}\right]\)
(3) \(\left[\mathrm{ML}^3 \mathrm{~T}^{3}\right]\)
(4) \(\left[\mathrm{ML}^2 \mathrm{~T}^{3}\right]\)
Answer: (1) \(\left[\mathrm{ML}^2 \mathrm{~T}^{-3}\right]\)
Question 53. 1 watt =
(1) \({10}^5\) erg/sec
(2) \({10}^6\) erg/sec
(3) \({10}^7\) erg/sec
(4) \({10}^8\) erg/sec
Answer: \({10}^7\) erg/sec
Question 54. What is the practical unit of power in CGS system?
(1) Erg
(2) Watt
(3) Joule
(4) Newton
Answer: (2) Watt